Messages to promote a walking habit: a large-scale experiment

Last registered on November 30, 2022


Trial Information

General Information

Messages to promote a walking habit: a large-scale experiment
Initial registration date
November 28, 2022

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
November 30, 2022, 4:22 PM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.



Primary Investigator


Other Primary Investigator(s)

PI Affiliation
University of Copenaghen

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Walking 10k steps a day has relevant benefits for health and is feasible for the vast majority of people. Moreover, walking is the most sustainable way to move. The project aims to test the effectiveness of specific messages on the steps subjects walk. These messages are built based on behavioral features which can be useful in increasing the number of steps made: sunk cost as a self-management device, social comparison, and inter-temporal comparison. We want to test if these messages can be superior to standard reminders in the short and long run. Subjects will be randomized to receive a standard reminder or messages that use behavioral tools. We will also collect data about subjects who do not receive any reminders. Duration of the exposition to the message will vary from 1 to 3 weeks to test time effects. Data will be collected using an app and the experiment aims to involve 20000 users.
External Link(s)

Registration Citation

Braut, Beatrice and Sarah Zaccagni. 2022. "Messages to promote a walking habit: a large-scale experiment." AEA RCT Registry. November 30.
Sponsors & Partners

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Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
nr of daily steps, probability of walking 10k steps a day
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
we will randomize users of the app that opt-in to receive messages to one of the possible conditions:
- standard reminder (Control)
- message about sunk costs (Treatment1)
- message with info about other users' steps (Treatment2)
- messages about their own number of steps in the prev day (Treatment3)
All the subjects will receive the standard reminder for two weeks, then will be allocated to the control or one of the treatments. these will last 1 week for half of the sample, 3 weeks for the other, and then go back to the standard message.
We will collect the number of daily steps for the period just after the intervention (weeks) and some months after, according to data availability.
Experimental Design Details
C: Hey, N'oubliez pas de valider vos pas ! C'est le moment d'augmenter sa cagnotte"
T1 "Hey, vous avez bien validé vos pas ces derniers jours, faites-le encore pour remporter plus de Wards"
T2 "Aujourd'hui, les WeWarders ont fait XXXX pas en moyenne, et vous ?"
T3 "La semaine dernière, vous avez marché en moyenne XXXX pas, combien en avez-vous fait aujourd'hui ?"
Randomization Method
random assignment of users to groups
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials